Forecasting the arrival time of the CME’s shock at the Earth Evangelos Paouris and Helen Mavromichalaki Athens Space Weather Forecasting Center, Cosmic Ray Group, Faculty of Physics, National and Kapodistrian University of Athens 28 November 2017, Ostend, Belgium

Evangelos Paouris ESWW14 28 November 2017 Overview New ICMEs database Effective Acceleration Model – EAMv1 Projection effects – New EAMv2 Statistics – bootstrap method Summary – Future work Evangelos Paouris ESWW14 28 November 2017

Evangelos Paouris ESWW14 28 November 2017 The new ICMEs database Jan 1996 – Dec 2009 266 ICMEs 51 columns Available at: http://cosray.phys.uoa.gr/index.php/icmes Evangelos Paouris ESWW14 28 November 2017

Effective Acceleration Model Arrival time of the CME r = 0.95 Pred. levels: 99% r = 0.98 Slow CMEs accelerating while the fast ones decelerating (Paouris and Mavromichalaki, 2017) Evangelos Paouris ESWW14 28 November 2017

Effective Acceleration Model Almost 47.7% of the examined events had the maximum 3-hour value of geomagnetic Ap-index during the sheaths (Paouris and Mavromichalaki, 2017) Replacing the velocity inside the ICME with the velocity inside the sheath (Paouris and Mavromichalaki, 2017b) «Community Coordinated Modeling Center – CCMC» NASA (https://swrc.gsfc.nasa.gov/main/cmemodels) Evangelos Paouris ESWW14 28 November 2017

Effective Acceleration Model for CME’s shock Arrival time of the CME’s shock Total 266 events with Shock 222 (214 without any data gaps) r = 0.98 Evangelos Paouris ESWW14 28 November 2017

Effective Acceleration Model v1 CME linear speed u (from e.g. CACTUS or our IDL code) How it works? Credit: SOHO/LASCO 1 AU Credit: NASA Outputs: Arrival time of the CME’s shock Acceleration / Deceleration Speed of the shock at 1 AU Inputs: onset time linear speed Code IDL (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Projection effects The speed of a CME (u) which is calculated by white light coronagraph data is possible to be a slight different than the actual radial speed of the CME. This is due to the projection effects as this speed is measured on the plane of the sky. (Gopalswamy et al., 2001; Leblanc et al., 2001; Xie et al., 2006; Vrsnak et al., 2007) Taking into account projection effects ur : radial speed u0 : speed of CME from coronagraphs α : cone angle (half angular width) φ : calculated from the coordinates of the active region (Leblanc et al., 2001) (Sheeley et al., 1999) Credit: SOHO/LASCO Where ψ and λ are the longitude and latitude of the active region (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Radial speed vs Linear speed From the 118 events the 87 were associated with solar flares = known coordinates! Excluding halo CMEs (148) Total 266 events r ≈ 0.99 (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Using CME radial speed CME radial speed CME speed from LASCO Improved version: Taking into account projection effects! (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Effective Acceleration Model v2 Evangelos Paouris ESWW14 28 November 2017

Statistics for two versions EAMv1 EAMv2 <T> = +3.03 hours Standard error = +1.53 h Median = +4.17 h min T = -64.23 h max T = +55.98 h MAE = 18.58 h RMSE = 22.47 h <T> = -0.28 hours Standard error = +1.48 h Median = +0.35 h min T = -65.17 h max T = +52.02 h MAE = 17.65 h RMSE = 21.55 h MAE: Mean Absolute Error RMSE: Root Mean Squared Error (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Statistics for two versions Statistical parameter Simple Bootstrap method with replacement for 1×107 runs Table 5 Summary of the statistical parameters for both models using a sample of 214 ICMEs of the duration (T) between the predicted arrival time and the actual arrival time of the shock T = tpred – tshock. The error of the average is on the mean of all events. The error bars for the other parameters are estimated using a simple bootstrap method with replacement for 107 times. All results are in hours. Statistical parameter EAMv1 EAMv2 Original Sample Bootstrapped results with errors Average +3.03 +3.03±1.52 -0.28 -0.28±1.47 Median +4.17 +3.90±1.83 +0.35 +0.47±1.88 Standard deviation +22.32 +22.24±0.98 +21.60 +21.53±0.96 MAE +18.58 +18.58±0.86 +17.65 +17.65±0.84 RMSE +22.47 +22.45±0.95 +21.55 (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Test case – 3 Earth directed CMEs Table 1 Predicted arrival time of the shock driven by the CME of 23 May 2017 06:00UT by three models. The difference time between this time and the actual arrival time of the shock (in hours) is also given. Model Prediction Difference (hours) WSA-ENLIL + Cone (GSFC SWRC) 2017-05-26 18:00 UT -20.78 WSA-ENLIL + Cone (Met Office) 2017-05-26 15:00 UT -23.78 EAMv1 (ASWFC) 2017-05-27 21:07 UT +6.33 Table 2 Predicted arrival time of the shock driven by the CME of 28 June 2017 16:24UT by three models. The difference between this time and the actual arrival time of the shock (in hours) is also presented. Model Prediction Difference (hours) WSA-ENLIL + Cone (Met Office) 2017-07-02 21:00 +28.60 WSA-ENLIL + Cone (GSFC SWRC) 2017-07-02 19:30 +27.10 EAMv1 (ASWFC) 2017-07-03 04:50 +36.40 Positive time difference means that the prediction time was later than the actual arrival time of the shock and vice versa for negative values. Table 3 Predicted arrival time of the shock driven by the CME of 14 July 2017 01:36UT by different models. The difference between this time and the actual arrival time of the shock (in hours) is also presented. Model Prediction Difference (hours) WSA-ENLIL + Cone (NOAA/SWPC) 2017-07-16 18:00 +12.77 DBM (SIDC) 2017-07-16 12:00 +6.77 WSA-ENLIL + Cone (Met Office) 2017-07-16 15:00 +9.77 WSA-ENLIL + Cone (GSFC SWRC) 2017-07-16 21:42 +16.47 SARM 2017-07-16 08:53 +3.65 Ensemble WSA-ENLIL + Cone (GSFC SWRC) 2017-07-16 16:51 +11.62 EAMv1 (ASWFC) 2017-07-16 08:48 +3.57 Visit CME Scoreboard: https://kauai.ccmc.gsfc.nasa.gov/CMEscoreboard/ (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Comparison between two versions for 3 events Table 4 Predicted and actual arrival times of the three CMEs shocks with the EAMv1 and EAMv2 models. The difference between these times (in hours) is also presented. CME (date and time UT) Shock arrival time (date and time UT) Predicted arrival date and time EAM-v1 Difference (hours) EAM-v2 23-05-2017 06:00 27-05-2017 14:47 27/05/2017 21:07 +6.33 27/05/2017 17:55 +3.15 28-06-2017 16:24 01-07-2017 16:26 03/07/2017 04:50 +36.40 03/07/2017 01:27 +33.03 14-07-2017 01:36 16-07-2017 05:14 16/07/2017 08:48 +3.57 16/07/2017 05:33 +0.33 This new version improved all the forecasted events (Paouris and Mavromichalaki, 2017b) Evangelos Paouris ESWW14 28 November 2017

Summary – Future work A new database of 266 interplanetary coronal mass ejections (ICMEs) with as much information as possible is introduced A new model for the estimation of the effective acceleration firstly introduced on Paouris and Mavromichalaki (2017) This model using simple equations of motion estimates the arrival time of the CME (main part) A new version of this simple model (EAMv1) is introduced for the forecast of the arrival time of the shock that preceds a CME and at the same time this version becomes one of the registered methods-models of the CCMC CME Scoreboard providing predictions for Earth directed CMEs For the first time, the projection effects of the linear speed of CMEs are taken into account in this empirical model (EAMv2), which significantly improves the prediction of the arrival time of the shock Future work: Study the interaction with the ambient solar wind – connection with the background conditions of the interplanetary space before the arrival of the CME Prediction of Bz component at 1 AU using ICMEs database Evangelos Paouris ESWW14 28 November 2017

Paouris, E. and Mavromichalaki, H Paouris, E. and Mavromichalaki, H., “Interplanetary Coronal Mass Ejections Resulting from Earth-Directed CMEs Using SOHO and ACE Combined Data During Solar Cycle 23”, Solar Physics, (2017) 292: 30. DOI: 10.1007/s11207-017-1050-2. Paouris, E. and Mavromichalaki, H., “Effective Acceleration Model for the Arrival Time of Interplanetary Shocks driven by Coronal Mass Ejections”, Solar Physics, (2017) 292: 180. DOI: 10.1007/s11207-017-1212-2. Thank you! Athens Space Weather Forecasting Center, Cosmic Ray Group, Faculty of Physics, National and Kapodistrian University of Athens Evangelos Paouris ESWW14 28 November 2017